Electric cut-out



March 27, 1934. O mTTENHOUSE 1,952,460

ELECTRIC CUT-OUT Filed July 11. 193?.

mmmuummn zflfilllllllllllll 2 INVENTOR 01in Pitts 717101156 ATTORNEY Patented Mar. 27, 1934 iJNiTED STATES 1 Claim.

This invention relates to electric cut-outs, and particularly to that kind of cut-out comprising a fuse plug and socket, said fuse plugs being designed to different electric leads correspond- 5 ing to the maximum amperage of the circuit in which they are to be employed.

The principal object of this invention is the provision of cooperating sockets and plugs which are simple in construction, inexpensive to make,

andwhich are so constructed that a plug of high amperage w ll not make the contact when used with a socket of low amperage, and vice versa.

To these and other ends, the invention consists in the construction and arrangement of parts that will appear from the following description when read in conjunction with the accompanying drawing, the novel features be ing pointed out in the claims at the end of the specification.

In the drawing:

Fig. 1 is a central Vertical section of a fuse plug constructed according to one possible embodiment of the invention;

Fig. 2 is a similar view of a cooperating socket;

Fig. 3 is a front elevation of a stud for adapting the plug shown in Fig. 1 for use with a socket of ordinary or usual construction;

Fig. 4 is a central vertical section of a plug designed to be used with a socket in a circuit of different amperage from that shown in Fig. 1;

Fig. 5 is a central vertical section of a socket designed to cooperate with a plug such as that shown in Fig. 4;

Figs. 6 and '7 are views similar to Fig. 4. of plugs designed to carry loads of still different amperages, and

Figs. 8 and 9 are central vertical sections of sockets designed to cooperate respectively with 40 the plugs shown in Figs. 6 and '7.

Referring particularly to the drawing, the invention is illustrated applied to a cut-out of well known form, and comprises a socket l preferably constructed of suitable insulating material having an opening or recess 2 in its upper face and a centrally arranged opening in its base communicating with the bottom of the opening 2 and preferably concentric therewith. This latter opening is internally threaded for cooperation with a post in the form of a headed screw 3 threaded therein from below. However, the post may be secured in the socket by any suitable means. The lower end of the opening may be counter bored, as shown, to receive the head of the screw. One of the conductor terminals l is connected with the screw and the outer or lower end of the opening may cc sealed, as shown, with any suitable insulating material. The screw 3 projects into the opening fr .1 its bottom, and has a sleeve 5 of high com ac" tivity detachably threaded thereon, the upper end 6 of which serves as a terminal or Contact point.

The opening or recess 2 has a threaded lining '2 of high conductivity secured therein, which is connected with the other conductor 8 and serves as a terminal therefor. The plug 11, own Fig. 1 of the drawing, is constructed of suitable insulating material and comprises a knurled fingerpiece 12 at one end and its other end has a centrally arranged opening 13 therein. A contact member 1a is seated in said opening which is connected with a threaded casing or thimble 15 of high conductivity secured on the outer wall of the plug. A fusible safety link 16 adapt ed to carry an electric current of given amperage connects the contact 14 with the casing 15. The threaded casing 15 cooperates with the lining '7 in the socket when the plug is threaded therein. The distance from the contact mem ber 14-. to the lower end or" the plug may be substantially the same as the length of the sleeve 5 or less, so that when the plug is screwed into the socket, the contact 14 contacts the upper end of the sleeve and closes the circuit between the conductors 4 and 8 through the fusible safety link 16.

Means are provided for adapting the plug 11 for use with the ordinary socket having a contact at the bottom of the opening 2. To this end, the lower or outer end of the opening 13 in the plug is threaded for cooperation with a stud 1'7, shown in Fig. 3, which may be threaded therein into contact with the contact 14 and at its outer end adapted to engage the contact at the bottom 5 of the socket opening.

The tubular members 5 may be made of various heights. Corresponding plugs 11 for cooperation therewith would have the contacts 14 arranged at various distances from the lower or inner end of the plug to correspond to and cooperate with the socket contacts of different heights or elevations. In such a system, if a socket having its contact at lowest elevation were used in the circuit of least amperage, and the sockets having contacts at higher elevation were progressively used in circuits of progressively greater amperage, none of the plugs except the one especially constructed for use therewith or one of lower amperage would serve to close its circuit, or in to overload any circuit.

In Figs. 4, 6 and 7 are shown fuse plugs 21, 22 and 23 respectively, which are of well known type and similar to each other except that tabular portions 24, 25 and 26 are of different lengths for cooperation with contacts 27, 28 and 29 respectively in sockets 31, 32 and 33 similar to the socket l in all respects, except that they are arranged at progressively greater distances from the bottom walls of the openings or recesses in the sockets. The contact 28 is arranged at the least distance from the bottom wall of the opening and the rcatest distance from the upper end thereof, and the contact 29 is at the greatest distance from the bottom wall of the opening in its socket and nearest the upper end thereof, wh le the contact 28 is shown in an intermediate position.

The plugs shown in Figs. and 7 are not interchangeable with the plug 11 in the socket 1 since the plugs engage the upper end of the sleeve and prevent the interengagement of the threads on the plug with those in the socket. It is also impossible to close the circuit in any of the sockets 31, 32 or 33 with the plug 11, since the inner end of the plug engages the bottom of the opening in the socket or its fingerpiece engages the top of the socket before the contact closes the circuit. In a system comprising two circuits, such as domestic lighting systems which are usually wired for either or amperes of current, one of sockets shown in 5, S or 9 with its cooperating plug could be used in one of the circuits and the socket l and its cooperating plug 11 in the other, and neither plug would lit a socket in the other circuit. :1 such a systern, it is not only impossible to overload a cirbut it is impossible to use a weaker fuse in a stronger circuit, which would blow soon as the current became too strong for the fusible link.

I claim:

The combination with a socket, of a fuse plug engageable therewith and having means at its outer end for limiting its movement into the socket, the socket having a centrally arranged opening in its base, a post extending through said opening and projecting into the interior of the socket, said post having a head abutting the outer surface of the socket adjacent opening, and a sleeve having threaded engagement with the inner end of the post and abutting the inner surface of the socket adjacent said opening, sleeve being of such length that its inner end makes contact with the inner end of the plug when the latter is screwed into the socket to its innermost position.

OLIN RITTENHOUSE.

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